Benzopyrans for use in recording systems

ABSTRACT

Benzopyrans of the formula ##STR1## where X is a radical ##STR2## and R 1 , R 2 , R 3 , R 4  and the ring A have the meanings stated in the description, a process for their preparation, and their use in pressure-sensitive or heat-sensitive layers.

This is a division of application Ser. No. 07/025,063, filed Mar. 12, 1987 now U.S. Pat. No. 4,841,050.

The present invention relates to novel benzopyrans which have a side chain in ring position 2, a process for their preparation and their use in pressure-sensitive or heat-sensitive recording systems.

We have found benzopyrans of the general formula I ##STR3## where R¹ is unsubstituted or substituted C₁ -C₈ -alkyl, unsubstituted or substituted phenyl, C₁ -C₅ -alkoxy or halogen, X is a radical ##STR4## R² is hydrogen or, together with R¹, is C₂ - or C₃ -alkylene which is unsubstituted or substituted by C₁ -C₄ -alkyl, R³ is phenyl which is unsubstituted or substituted by C₁ -C₄ -alkyl (which in turn may be substituted by phenyl), cyclohexyl, halogen, C₁ -C₈ -alkoxy, C₁ -C₈ --mono- or dialkylamino (each of which in turn may be substituted by phenyl or chlorine), phenylamino (which in turn may be substituted by C₁ -C₈ -alkyl on the phenyl ring or on the nitrogen atom), pyrrolidino, piperidino or morpholino, and which furthermore may be substituted by C₁ -C₅ -alkyl, C₁ -C₅ -alkoxycarbonyl, C₁ -C₅ -dialkylaminocarbonyl, pyrrolidinocarbonyl, piperidinocarbonyl, morpholinocarbonyl, C₁ -C₈ -alkoxy or halogen; or is naphthyl which is unsubstituted or substituted by C₁ -C₄ -alkoxy; or is carbazol-3-yl or 1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, each of which may be substituted on the nitrogen atom by C₁ -C₅ -alkyl or benzyl, or is indol- 3-yl, which may be substituted in ring position 1 and/or 2 by unsubstituted or phenyl-substituted C₁ -C₅ -alkyl; or is thiazol-₅ -yl which is substituted in ring position 2 by unsubstituted or phenyl-substituted C₁ -C₅ -mono- or dialkylamino, pyrrolidino, piperidino or morpholino and may be substituted in ring position 4 by C₁ -C₅ -alkyl, phenyl or chlorine, and R⁴ is hydroxyl, C₁ -C₅ -alkoxy, unsubstituted or substituted phenoxy, unsubstituted or substituted phenylsulfonyl, pyrrolidino, piperidino, morpholino or a radical of a CH-acidic compound, and the ring A may be fused, to a benzo ring, may be substituted by C₁ -C₄ -alkyl, chlorine or bromine, or may be substituted in ring position 7 by C₁ -C₅ -mono- or dialkylamino (each of which in turn may be substituted by chlorine or phenyl), pyrrolidino, piperidino, morpholino, hydroxyl or C₁ -C₄ -alkoxy.

All alkyl groups occurring in the abovementioned radicals may be either straight-chain or branched.

In formula I, R¹ is, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isoamyl, hexyl, heptyl, octyl, 2-ethylhexyl, phenyl which is unsubstituted or substituted by C₁ -C4-alkyl, C₁ -C₄ -alkoxy or halogen, such as 4-methylphenyl, 2-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-methoxyphenyl, 2ethoxyphenyl, 4-chlorophenyl or 2,4-dichlorophenyl, methoxy, ethoxy, propoxy, isopropoxy, butoxy, fluorine, chlorine or bromine.

In formula I, R² is, for example, hydrogen or, together with R¹, is 1,2-ethylene, 1,2-propylene or 1,3-propylene.

In formula I, R³ is, for example, phenyl or, preferably, phenyl which is substituted in ring position 4 by methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, benzyl, 2-phenylethyl, cyclohexyl, fluorine, chlorine, bromine, methoxy, ethoxy, propoxy, isopropoxy, butoxy, pentyloxy, hexyloxy, 2-ethylhexyloxy, methylamino, ethylamino, isopropylamino, butylamino, 2-ethylhexylamino, benzylamino, 2-chloroethylamino, dimethylamino, diethylamino, dibutylamino, methylethylamino, di(2-ethylhexyl) amino, anilino, 4-methylanilino, 4-ethylanilino, N-methylanilino, N-ethylanilino, pyrrolidino, piperidino or morpholino; or is, for example, 2,4-dimethylphenyl, 2-methoxycarbonyl-4-dimethylaminophenyl, 2-ethoxycarbonyl-4-dimethylaminophenyl, 2-dimethylaminocarbonyl-4-methoxyphenyl, 2-pyrrolidinocarbonyl-4-methylphenyl, 2-piperidinocarbonyl-4-dimethylaminophenyl, 2-morpholinocarbonyl-4-methylphenyl, 2,4-dimethoxyphenyl, 3,4-dimethoxyphenyl, 2-methoxy-4-dimethylaminophenyl, 2-methoxy-4-dibenzylaminophenyl, 2,4-dichlorophenyl, naphthyl, 4-methoxynaphthyl, carbazol-3-yl, N-methylcarbazol-3-yl, N-ethylcarbazol-3-yl, N-benzylcarbazol-3-yl, 1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, N-methyl-1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, N-ethyl-1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, N-benzyl-1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, indol-3-yl, 1-methylindol-3-yl, 1-ethylindol-3-yl, 1-benzylindol-3-yl, 1-(2-phenylethyl)indol-3-yl, 2-methylindol-3-yl, 1,2-dimethylindol-3-yl, 1-benzyl-2-methylindol-3-yl, 2 -methylaminothiazol-5-yl, 2-dimethylaminothiazol-5-yl, 2-diethylaminothiazol-5-yl, 2-benzylaminothiazol-5-yl, 2-pyrrolidinothiazol-5-yl, 2-morpholinothiazol-5-yl, 4-methyl-2-dimethylaminothiazol-5-yl, 4-phenyl-2-benzylaminothiazol- 5-yl or 4-chloro-2-piperidinothiazol-5-yl.

In formula I, R⁴ is, for example, hydroxyl, methoxy, ethoxy, propoxy, isopropoxy, sec-butoxy or pentyloxy; phenoxy which is unsubstituted or substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or halogen, such as 2-methylphenoxy, 4-methylphenoxy, 3-methoxyphenoxy or 4-chlorophenoxy; phenylsulfonyl which is unsubstituted or substituted by C₁ -C₄ -alkyl or halogen, such as 4-methylphenylsulfonyl or 4-chlorophenylsulfonyl; pyrrolidino, piperidino or morpholino.

In formula I, R⁴ may furthermore be a radical of a CH-acidic compound, for example 2-(pyrrolidino, piperidino or morpholino)-cyclopent-1-en-1-yl or -cyclohex-1-en-1-yl; cyclohexane-1,3-dion-2-yl which is unsubstituted or monosubstituted or disubstituted in ring position 5 by C₁ -C₄ -alkyl, such as cyclohexane-1,3-dion-2-yl, 5-methylcyclohexane-1,3-dion-2-yl, 5-ethylcyclohexane-1,3-dion-2-yl or 5,5-dimethylcyclohexane-1,3-dion-2-yl; benzoylmethyl; cyano; nitromethyl; 2,4,6-trihydroxypyrimid-5-yl; 1-phenyl-3-methylpyrazol-5-on-4-yl; 5-hydroxy-3,4-dichlorfuran-2-yloxy; or a radical ##STR5## where Y and Z are identical or different and independently

of one another are each acetyl, benzoyl, C₁ -C₅ -alkoxycarbonyl or cyano, and, where Y is cyano, Z may furthermore be methyl, e.g. bis-(acetyl)-methyl, bis-(benzoyl)-methyl, bis-(methoxycarbonyl)-methyl, bis-(ethoxycarbonyl)-methyl, bis-(cyano)-methyl, acetyl-benzoyl-methyl, acetyl-methoxycarbonyl-methyl, benzoyl-ethoxycarbonyl-methyl, cyanomethoxycarbonyl-methyl, cyano-ethoxycarbonyl-methyl or 1-cyanoeth-1-yl.

In formula I, the ring A may be substituted, for example, in ring position 6 or 8 by chlorine or bromine or in ring position 6 and 8 by chlorine. It may furthermore be substituted in ring position 7 by, for example, methyl, ethyl, propyl, isopropyl, butyl, hydroxyl, methoxy, ethoxy, isopropoxy, methylamino, ethylamino, propylamino, isopropylamino, butylamino, benzylamino, 2-chloroethylamino, dimethylamino, diethylamino, dibutylamino, dibenzylamino, methylethylamino, pyrrolidino, piperidino or morpholino. It may also be benzofused, for example as follows: ##STR6##

Preferred benzopyrans of the formula I are those in which R¹ is C₁ -C₅ -alkyl, R² is hydrogen, R³ is carbazol-3-yl or unsubstituted or substituted phenyl and R⁴ is a radical ##STR7##

The novel benzopyrans are advantageously obtained if a benzopyrylium compound of the formula II ##STR8## where R¹ and the ring A have the above meaning and Y.sup.⊖ is an anion, is reacted with an aldehyde of the formula III

    R.sup.3 --CHO                                              (III)

where R³ has the above meanings, in a molar ratio of from 1:0.8 to 1:1.2, in the presence of an inert solvent at from 20° to 120° C., preferably from 40° to 80° C., and, in a subsequent stage, the resulting dye salt of the formula IV ##STR9## where R¹, R³, Y.sup.⊖ and the ring A have the above meanings, is reacted with a compound of the formula V

    R.sup.4 --H                                                (V)

where R⁴ has the above meanings, in a molar ratio of from 1:1.1 to 1:2, in the presence of an inert solvent and of a base at from 20° to 120° C., preferably from 40° to 80° C.

Examples of suitable anions Y.sup.⊖ are trichlorozincate, tetrachloroferrate(III), bisulfate, nitrate or halide, such as chloride or bromide. Trichlorozincate and tetrachloroferrate(III) are particularly preferred.

Examples of advantageously inert solvents are methanol, ethanol, propanol, isopropanol, butanol and sobutanol. Mixtures of these alcohols with aromatic hydrocarbons, such as toluene or xylene, may also be used as the reaction medium.

Examples of suitable bases for the reaction of the dye salt IV with the compound V are alkali metal and alkaline earth metal carbonates, such as sodium carbonate, potassium carbonate, magnesium carbonate or calcium carbonate, alkaline earth metal oxides, such as magnesium oxide or calcium oxide, and alkali metal alkanolates, such as sodium or potassium methylate, ethylate or butylate. In general, from 1 to 3 moles of base are added per mole of dye salt.

The benzopyrylium salts II, aldehydes III and compounds IV which are required for the novel process are known.

The benzopyrans according to the invention are pale or colorless compounds whose solutions in inert organic solvents, in contact with electron acceptors, give dyeings in yellow, orange, red or blue hues, depending on the substitution of the benzopyran. Examples of electron acceptors are carboxylic acids, mineral acids, kaolin, bentonite, activated clay, aluminum silicate, attapulgite or any clay, acidic polymeric materials, such as condensates based on phenol (and/or phenolsulfonic acids) and formaldehyde, as well as metal oxides or salts, such as zinc oxide, alumina, zinc chloride, iron stearate and cobalt naphthenate.

Because of these properties, the novel compounds of the formula I are useful as dye precursors in pressure-sensitive and heat-sensitive recording materials.

For use in pressure-sensitive systems the novel benzopyrans are advantageously enclosed in microcapsules, in the form of solutions in organic solvents, e.g. chloroparaffins, partially hydrogenated di- or terphenyl, alkylbenzenes, alkylnaphthalenes, alkylated dibenzylbenzenes, liquid paraffin, mineral oil or conventional lower-boiling solvents, such as xylene or toluene, and the carrier, e.g. paper, is coated with these microcapsules. When the microcapsules are subjected to pressure and are in contact with electron acceptors, dye formation then takes place at the pressure point.

Suitable processes for the preparation of microcapsules are disclosed in, for example, U.S. Pat. Nos. 2,800,457, 2,800,458, DE-A-No. 2 119 933 and EP-A-No. 26 914. It is also possible for the novel compounds to be finely dispersed in wax or oil/wax mixtures by the method described in U.S. Pat. No. 3,103,404, and carriers, such as films or paper, to be coated with these mixtures. The resulting pressure-sensitive materials are suitable for copying onto papers coated with electron acceptors, and can be removed after use, like carbon paper.

The novel benzopyrans can also be used as dye precursors in heat-sensitive recording materials which contain a binder, a dye precursor and an electron acceptor on a carrier. The structure of such heat-sensitive recording materials and the composition of the layers which produce the color under the effective heat are known (for example, DE-A-No. 2 228 581 and DE-A-No. 2 110 854), as are the processes and apparatuses which are used to produce the dye.

The Examples which follow illustrate the invention.

EXAMPLE 1 (a) Synthesis of the Dye Salt

331 g (1 mole) of 2,3-dimethylbenzopyrylium trichlorozincate and 149 g (1 mole) of 4-dimethylaminobenzaldehyde in 1,500 ml of methanol were refluxed for 4.5 hours. After the mixture had cooled, the precipitated dye was filtered off under suction and washed with methanol.

Yield: 400 g (86.6% of theory) mp.: 242°-244° C.

The dye salt of the formula ##STR10## is obtained.

(b) Synthesis of the Dye Precursor

46 g (0.1 mole) of the dye salt prepared under (a) and 20 g of benzoylacetone (0.13 mole) in 500 ml of methanol were stirred in the presence of 22 g (0.2 mole) of sodium carbonate at 45° C. The reaction mixture was then added to a mixture of 1,600 ml of toluene and 1,600 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. 500 ml of methanol were added, and the precipitate which formed was then filtered off under suction, washed with 200 ml of methanol and dried at 60° C. under reduced pressure.

Yield: 34 g (76%) mp.: 165°-167° C.

A dye precursor of the formula ##STR11## was obtained.

The components of the formula ##STR12## which are listed in Table 1 can be obtained in a similar manner.

                  TABLE 1                                                          ______________________________________                                         Example                                                                               R.sup.4        Mp. [°C.]                                                                        Color or λ.sub.max                       ______________________________________                                                                        [nm]                                                    ##STR13##     270-272  blue                                            3      CH(COC.sub.6 H.sub.5).sub.2                                                                   193-195  628.9                                           4      CH(CN).sub.2   194-196  628.9                                           5      CH.sub.2NO.sub.2                                                                              156-158  blue                                            ______________________________________                                    

EXAMPLE 6

(a) Synthesis of the Dye Salt

331 g (1 mole) of 2,3-dimethylbenzopyrylium trichlorozincate and 223 g (1 mole) of N-ethylcarbazole-3-aldehyde in 2,600 ml of methanol saturated with HCl are refluxed for 3 hours. After the mixture had cooled, the precipitated dye was filtered off under suction and washed with methanol.

Yield: 453 g (84.6% of theory) mp.: 240°-242° C.

A dye salt of the formula ##STR14## was obtained.

(b) Synthesis of the Dye Precursor

16 g (0.03 mole) of the dye salt prepared under (a) and 5 g (0.038 mole) of ethyl acetoacetate in 250 ml of methanol were stirred in the presence of 7 g (0.066 mole) of sodium carbonate at 45° C. The reaction mixture was then added to a mixture of 500 ml of toluene and 500 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. After the addition of 250 ml of methanol, the precipitate formed was filtered off under suction, washed with 70 ml of methanol and dried at 60° C. under reduced pressure.

Yield: 10 g (67.6% of theory) mp.: 132°-134° C.

A dye precursor of the formula ##STR15## was obtained.

The components of the formula ##STR16## which are listed in Table 2 can be obtained in a similar manner.

                  TABLE 2                                                          ______________________________________                                         Example                                                                               R.sup.4        Mp. [°C.]                                                                        Color or λ.sub.max                       ______________________________________                                                                        [nm]                                             7                                                                                     ##STR17##     156-158  blue                                             8     CH(COCH.sub.3).sub.2                                                                          147-149  607.4                                            9                                                                                     ##STR18##     126-128  606.9                                           10     OH             154-157  606.4                                           11     CH(COOC.sub.2 H.sub.5).sub.2                                                                  182-184  pale blue                                       12     CH(COC.sub.6 H.sub.5).sub.2                                                                   142-144  606.9                                           13     CH(CN).sub.2   241-243  607.4                                           14                                                                                     ##STR19##     193-195  607.9                                           15                                                                                     ##STR20##     187-189  607.9                                           16     CH.sub.2NO.sub.2                                                                              154-156  605.4                                           17     CH(COOCH.sub.3).sub.2                                                   ______________________________________                                    

The dye precursors of the formula ##STR21## which are listed in Table 3 can be obtained similarly to Examples 1 to 6.

                                      TABLE 3                                      __________________________________________________________________________                                                      Color or                      Example                                                                             R.sup.1   R.sup.3         R.sup.4      Mp. [°C.]                                                                    λ.sub.max              __________________________________________________________________________                                                      [nm]                          18   CH.sub.3                                                                                  ##STR22##                                                                                      ##STR23##   146-148                                                                             blue                          19   CH.sub.3                                                                                  ##STR24##      CH(CO-CH.sub.3).sub.2                                                                       142-144                                                                             pale lime green               20   CH.sub.3                                                                                  ##STR25##      CH(COC.sub.6 H.sub.5).sub.2                                                                 144-146                                                                             642.4                         21   CH.sub.3                                                                                  ##STR26##                                                                                      ##STR27##   203-205                                                                             blue                          22   CH.sub.3                                                                                  ##STR28##      CH(COCH.sub.3).sub.2                                                                        170-172                                                                             blue                          23   CH.sub.3                                                                                  ##STR29##                                                                                      ##STR30##   144-148                                                                             green                         24   CH.sub.3                                                                                  ##STR31##      CH(COC.sub.6 H.sub.5).sub.2                                                                 189  632.4                         25   CH.sub.3                                                                                  ##STR32##                                                                                      ##STR33##   184-186                                                                             blue                          26   CH.sub.3                                                                                  ##STR34##                                                                                      ##STR35##   oil  672.9/631.4                   27   CH.sub.3                                                                                  ##STR36##                                                                                      ##STR37##   128-130                                                                             671.9/630.9                   28   CH.sub.3                                                                                  ##STR38##      CH(COC.sub.6 H.sub.5).sub.2                                                                 132-134                                                                             672.9/630.4                   29   CH.sub.3                                                                                  ##STR39##      CH(CN).sub.2 203-205                                                                             blue                          30   CH.sub.3                                                                                  ##STR40##                                                                                      ##STR41##   oil  blue                          31   CH.sub.3                                                                                  ##STR42##                                                                                      ##STR43##   oil  blue                          32   CH.sub.3                                                                                  ##STR44##                                                                                      ##STR45##   154-156                                                                             blue                          33   CH.sub.3                                                                                  ##STR46##      OH           195  blue                          34   CH.sub.3                                                                                  ##STR47##      CH(COC.sub.6 H.sub.5).sub.2                                                                 178-180                                                                             519.3                         35   CH.sub.3                                                                                  ##STR48##      CH(COCH.sub.3).sub.2                            36   CH.sub.3                                                                                  ##STR49##                                                                                      ##STR50##                                      37   CH.sub.3                                                                                  ##STR51##      CH(COCH.sub.3).sub.2                                                                        165  reddish violet                38   CH.sub.3                                                                                  ##STR52##                                                                                      ##STR53##        reddish violet                39   CH.sub.3                                                                                  ##STR54##      CH(COCH.sub.3).sub.2                                                                         98-102                                                                             523.8                         40   CH.sub. 3                                                                                 ##STR55##                                                                                      ##STR56##   159-160                                                                             reddish violet                41   CH.sub.3                                                                                  ##STR57##      OH           136-140                                                                             pale red                      42   CH.sub.3                                                                                  ##STR58##                                                                                      ##STR59##   oil  542.8                         43   CH.sub.3                                                                                  ##STR60##      OH           120-124                                                                             reddish violet                44   CH.sub.3                                                                                  ##STR61##      CH(COCH.sub.3).sub.2                                                                             violet                        45   CH.sub.3                                                                                  ##STR62##      OH           210-216                                                                             violet                        46   CH.sub.3                                                                                  ##STR63##      CH(COCH.sub.3).sub.2                                                                        141-145                                                                             pink                          47   CH.sub.3                                                                                  ##STR64##      CH(COCH.sub.3).sub.2                                                                        oil  orange                        48   CH.sub.3                                                                                  ##STR65##      OH           oil  orange                        49   CH.sub.3                                                                                  ##STR66##      CH(COCH.sub.3).sub.2                                                                        118  yellow                        50   CH.sub.3                                                                                  ##STR67##                                                                                      ##STR68##   155  yellow                        51   CH.sub.3                                                                                  ##STR69##                                                                                      ##STR70##   163-168                                                                             647.9                         52   CH.sub.3                                                                                  ##STR71##      CH(COCH.sub.3).sub.2                                                                        oil  blue                          53   CH.sub.3                                                                                  ##STR72##                                                                                      ##STR73##   oil  blue                          54   CH.sub.3                                                                                  ##STR74##                                                                                      ##STR75##   181-183                                                                             blue                          55   CH.sub.3                                                                                  ##STR76##      CH(COCH.sub.3).sub.2                                                                        130-132                                                                             blue                          56   CH.sub.3                                                                                  ##STR77##      CH(COC.sub.6 H.sub.5).sub.2                                                                 166-168                                                                             644.9                         57   CH.sub.3                                                                                  ##STR78##      CH(CN).sub.2 221-223                                                                             643.9                         58   CH.sub.3                                                                                  ##STR79##      CH(COCH.sub.3).sub.2                                                                        198-200                                                                             573.3                         59   CH.sub.3                                                                                  ##STR80##                                                                                      ##STR81##   134-137                                                                             violet                        60   CH.sub.3                                                                                  ##STR82##                                                                                      ##STR83##        blue                          61   CH.sub.3                                                                                  ##STR84##                                                                                      ##STR85##   204-207                                                                             violet 549.3/583.8            62   CH.sub.3                                                                                  ##STR86##                                                                                      ##STR87##   oil  blue                          63   CH.sub.3                                                                                  ##STR88##                                                                                      ##STR89##   oil  blue                          64   CH.sub.3                                                                                  ##STR90##                                                                                      ##STR91##   oil  blue                          65   CH.sub.3                                                                                  ##STR92##      OH           215  violet                        66   C.sub.2 H.sub.5                                                                           ##STR93##                                                                                      ##STR94##   148-150                                                                             blue                          67   C.sub.2 H.sub.5                                                                           ##STR95##      CH(COCH.sub.3).sub.2                                                                        128-130                                                                             blue                          68   C.sub.2 H.sub.5                                                                           ##STR96##                                                                                      ##STR97##   166-168                                                                             blue                          69   C.sub.2 H.sub.5                                                                           ##STR98##      CH(COCH.sub.3).sub.2                                                                        131-135                                                                             blue                          70   CH(CH.sub.3).sub.2                                                                        ##STR99##                                                                                      ##STR100##  157-159                                                                             blue                          71   CH(CH.sub.3).sub.2                                                                        ##STR101##     CH(COCH.sub.3).sub.2                                                                        133-135                                                                             blue                          72   CH(CH.sub.3).sub.2                                                                        ##STR102##                                                                                     ##STR103##  153-155                                                                             633.4                         73   CH(CH.sub.3).sub.2                                                                        ##STR104##     CH(CN).sub.2 195-197                                                                             633.4                         74   CH(CH.sub.3).sub.2                                                                        ##STR105##                                                                                     ##STR106##  129-131                                                                             sky blue                      75   CH(CH.sub.3).sub.2                                                                        ##STR107##     CH(COCH.sub.3).sub.2                                                                        148-150                                                                             sky blue                      76   CH(CH.sub.3).sub.2                                                                        ##STR108##     CH(COCH.sub.3 ).sub.2                                                                       164-168                                                                             blue                          77   CH(CH.sub.3).sub.2                                                                        ##STR109##                                                                                     ##STR110##  118-120                                                                             605.4                         78   CH(CH.sub.3).sub.2                                                                        ##STR111##     CH(COC.sub.6 H.sub.5).sub.2                                                                 143-145                                                                             606.4                         79   CH(CH.sub.3).sub.2                                                                        ##STR112##                                                                                     ##STR113##  141-143                                                                             pale blue                     80   CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR114##                                                                                     ##STR115##  140-142                                                                             blue                          81   CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR116##     CH(COCH.sub. 3).sub.2                                                                       oil  blue                          82   CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR117##                                                                                     ##STR118##  163-165                                                                             pale blue                     83   CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR119##     CH(COCH.sub.3).sub.2                                                                        oil  greenish blue                 84   CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR120##     CH(COCH.sub.3).sub.2                                                                        oil  blue to bluish green          85                                                                                   ##STR121##                                                                               ##STR122##     CH(COCH.sub.3).sub.2                                                                        oil  blue                          86                                                                                   ##STR123##                                                                               ##STR124##                                                                                     ##STR125##  oil  blue                          87                                                                                   ##STR126##                                                                               ##STR127##     CH(COCH.sub.3).sub.2                                                                        oil  blue                          88                                                                                   ##STR128##                                                                               ##STR129##                                                                                     ##STR130##  oil  blue                          89                                                                                   ##STR131##                                                                               ##STR132##                                                                                     ##STR133##  179-181                                                                             greenish blue                 90                                                                                   ##STR134##                                                                               ##STR135##     CH(COCH.sub.3).sub.2                                                                        oil  greenish blue                 91                                                                                   ##STR136##                                                                               ##STR137##     OCH.sub.3         greenish blue                 92                                                                                   ##STR138##                                                                               ##STR139##                                                                                     ##STR140##  oil  greenish blue                 93                                                                                   ##STR141##                                                                               ##STR142##                                                                                     ##STR143##  180-182                                                                             blue                          94                                                                                   ##STR144##                                                                               ##STR145##                                                                                     ##STR146##  198-200                                                                             blue                          95                                                                                   ##STR147##                                                                               ##STR148##     CH(COCH.sub.3).sub.2                                                                        162-164                                                                             blue                          96   OCH.sub.3                                                                                 ##STR149##                                                                                     ##STR150##  182  blue                          97   OCH.sub.3                                                                                 ##STR151##     CH(COCH.sub.3).sub.2                                                                        168-170                                                                             blue                          98   OCH.sub.3                                                                                 ##STR152##                                                                                     ##STR153##  100-112                                                                             blue                          99   OCH.sub.3                                                                                 ##STR154##     CH(COCH.sub.3).sub.2                                                                        oil  blue                          100  OCH.sub.3                                                                                 ##STR155##     CH(COCH.sub.3).sub.2                                                                        183-185                                                                             blue                          __________________________________________________________________________

EXAMPLE 101

The following dye precursor was obtained similarly to Example 1: ##STR156##

EXAMPLE 102 (a) Synthesis of the Dry Salt

24 g (0.1 mole) of bis-(4-formylphenyl)-methylamine and 66 g (0.2 mole) of 2,3-dimethylbenzopyrylium trichlorozincate in 200 ml of methanol were refluxed for hours, 200 ml of methylglycol were added and refluxing was then continued for a further 1/2 hour. The mixture was cooled, and the solvent was then separated off from the precipitated dye.

Yield: 66 g mp.: 110° C.

(b) Synthesis of the Dry Precursor

26 g (0.03 mole) of the dye salt prepared under (a) and 8 g (0.08 mole) of acetylacetone were heated at 50° C. for 3 hours in the presence of 14 g (0.13 mole) of sodium carbonate in a mixture of 200 ml of methanol and 100 ml of toluene. The reaction mixture was then added to a mixture of 500 ml of toluene and 500 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. The residue was added dropwise to ice-cooled methanol, and the precipitate formed was filtered off under suction at 0° C.

Yield: 7 g mp.: 166°-168° C.

A dye precursor of the formula ##STR157## was obtained

The dye salt prepared in Example 102a was used and the following dye precursor was obtained by a method similar to that described in Example 102b: ##STR158##

EXAMPLE 104 (a) Synthesis of the Dye Salt

66 g (0.2 mole) of 2,3-dimethylbenzopyrylium trichlorozincate and 33 g (0.1 mole) of ethylenebis-[N-ethyl-N-(4-formylphenyl)]-amine in 400 ml of methanol were refluxed for 4 hours. After the mixture had cooled, the precipitated dye was filtered off under suction and washed with methanol.

Yield: 82 g mp.: 255°-260° C.

(b) Synthesis of the Dye Precursor

28.5 g (0.03 mole) of the dye salt prepared under (a) and 13 g (0.08 mole) of benzoylacetone were stirred under reflux for 7 hours in the presence of 15 g (0.14 mole) of sodium carbonate in a mixture of 350 ml of methanol and 100 ml of toluene. The reaction mixture was then added to a mixture of 500 ml of toluene and 500 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. The residue was diluted with methylglycol, and methanol was added. The precipitate formed was filtered off under suction, washed with methanol and dried at 60° C. under reduced pressure.

Yield: 7 g mp.: 132°-140° C.

A dye precursor of the formula ##STR159## was obtained.

EXAMPLE 105 (a) Synthesis of the Dye Salt

21.9 g (0.05 mole) of 2-cyclohexylidene-2,3,4,5-tetrahydroxanthylium trichlorozincate and 7.2 g (0.05 mole) of indoline-3-carbaldehyde in 320 ml of n-butanol were refluxed for one hour. The dye precipitated after the mixture had been cooled was filtered off under suction

Yield: 21 g mp.: 243°-245° C.

A dye salt of the formula ##STR160## was obtained.

(b) Synthesis of the Dye Precursor

9.7 g (0.02 mole) of the dye salt prepared under (a) and 2.7 g (0.027 mole) of acetylacetone in 100 ml of methanol were stirred in the presence of 4.7 g (0.044 mole) of sodium carbonate for 4 hours at 45° C. The reaction mixture was then added to a mixture of 300 ml of toluene and 300 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. After the addition of 100 ml of methanol, the precipitate formed was filtered off under suction, washed with 40 ml of methanol and dried at 60° C. under reduced pressure.

Yield: 5 g mp.: 162°-170° C.

A dye precursor of the formula ##STR161## was obtained. 

We claim:
 1. A benzopyran of the formula I: ##STR162## wherein R¹ is C₁₁ -C₈ -alkyl, phenyl, phenyl substituted with C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or halogen, C₁ -C₅ -alkoxy or halogen, X is a radical ##STR163## wherein R² is hydrogen, R³ is phenyl, phenyl substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkyl substituted by phenyl, cyclohexyl, halogen, C₁ -C₈ -alkoxy, C₁ -C₈ -monoalkylamino, C₁ -C₈ -monoalkylamino substituted by phenyl or chlorine, C₁ -C₈ -dialkylamino, C₁ -C₈ -dialkylamino substituted by phenyl or chlorine, phenylamino, phenylamino substituted on the phenyl ring or on the nitrogen atom by C₁ -C₈ -alkyl, naphthyl or naphthyl substituted by C₁ -C₄ -alkoxy; and R⁴ is hydroxyl, C₁ -C₅ -alkoxy, phenoxy, phenoxy substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or halogen, phenylsulfonyl, phenylsulfonyl substituted by C₁ -C₄ -alkyl or halogen or the radical --CHYZ, wherein Y and Z are identical or different and independently of one another are each acetyl, benzoyl, C₁ -C₅ -alkoxycarbonyl or cyano, and where when Y is cyano, Z may also be methyl; ring A is unfused or fused to a benzo ring, wherein ring A is unsubstituted or substituted by C₁ -C₄ -alkyl, chlorine or bromine or substituted in ring position 7 by C₁ -C₅ -monoalkylamino, C₁ -C₅ -dialkylamino, C₁ -C₅ -monoalkylamino substituted by chlorine or phenyl, C₁ -C₅ -dialkylamino substituted by chlorine or phenyl, hydroxyl or C₁ -C₄ -alkoxy.
 2. The benzopyran of claim 1, wherein R¹ is C₁ -C₈ -alkyl, C₁ -C₅ -alkoxy or halogen.
 3. The benzopyran of claim 1, wherein R¹ is phenyl or phenyl sustituted with C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or halogen.
 4. The benzopyran of claim 1, wherein R³ is phenyl, phenyl substituted by C₁ -C₄ -alkyl or C₁ -C₄ -alkyl substituted by phenyl.
 5. The benzopyran of claim 1, wherein R³ is cyclohexyl, halogen or C₁ -C₈ -alkoxy.
 6. The benzopyran of claim 1, wherein R³ is C₁ -C₈ -monoalkylamino, C₁ -C₈ -monoalkylamino substituted by phenyl or chlorine, C₁ -C₈ -dialkylamino, C₁ -C₈ -dialkylamino substituted by phenyl or chlorine, phenylamino or phenylamino substituted on the phenyl ring or on the nitrogen atom by C₁ -C₈ -alkyl.
 7. The benzopyran of claim 1, wherein R³ is naphthyl or naphthyl substituted by C₁ -C₄ -alkoxy.
 8. The benzopyran of claim 1, wherein R⁴ is hydroxyl or C₁ -C₅ -alkoxy.
 9. The benzopyran of claim 1, wherein R⁴ is phenoxy, phenoxy substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or halogen.
 10. The benzopyran of claim 1, wherein R⁴ is phenylsulfonyl or phenylsulfonyl substituted by C₁ -C₄ -alkyl.
 11. The benzopyran of claim 1, wherein R⁴ is said radical --CHYZ.
 12. The benzopyran of claim 1, wherein said ring A is fused to a benzo ring.
 13. The benzopyran of claim 1, wherein said ring A is unsubstituted.
 14. The benzopyran of claim 1, wherein said ring A is substituted by C₁ -C₄ -alkyl, chlorine or bromine.
 15. The benzopyran of claim 1, wherein said ring A is substituted in ring position 7 by C₁ -C₅ -monoalkylamino, C₁ -C₅ -dialkylamino, C₁ -C₅ -monoalkylamino substituted by chlorine or phenyl or C₁ -C₅ -dialkylamino substituted by chlorine or phenyl.
 16. The benzopyran of claim 1, wherein said ring A is substituted in ring position 7 by hydroxy or C₁ -C₄ -alkoxy. 